Jorma Ilonen

Intestinal virome changes precede autoimmunity in type I diabetes-susceptible children

Significance Type 1 diabetes (T1D) is a major autoimmune disease with increasing incidence in recent years. In this study, we found that the intestinal viromes of cases were less diverse than those of controls. We identified eukaryotic viruses and bacteriophage contigs that are associated with the presence or absence of autoimmunity. These viruses provide targets for future mechanistic studies to differentiate causal and incidental associations between the virome and protection against the development of T1D. Viruses have long been considered potential triggers of autoimmune diseases. Here we defined the intestinal virome from birth to the development of autoimmunity in children at risk for type 1 diabetes (T1D). A total of 220 virus-enriched preparations from serially collected fecal samples from 11 children (cases) who developed serum autoantibodies associated with T1D (of whom five developed clinical T1D) were compared with samples from controls. Intestinal viromes of case subjects were less diverse than those of controls. Among eukaryotic viruses, we identified significant enrichment of Circoviridae-related sequences in samples from controls in comparison with cases. Enterovirus, kobuvirus, parechovirus, parvovirus, and rotavirus sequences were frequently detected but were not associated with autoimmunity. For bacteriophages, we found higher Shannon diversity and richness in controls compared with cases and observed that changes in the intestinal virome over time differed between cases and controls. Using Random Forests analysis, we identified disease-associated viral bacteriophage contigs after subtraction of age-associated contigs. These disease-associated contigs were statistically linked to specific components of the bacterial microbiome. Thus, changes in the intestinal virome preceded autoimmunity in this cohort. Specific components of the virome were both directly and inversely associated with the development of human autoimmune disease.

Detection of enteroviruses in stools precedes islet autoimmunity by several months: possible evidence for slowly operating mechanisms in virus-induced autoimmunity

Aims/hypothesisThis case–control study was nested in a prospective birth cohort to evaluate whether the presence of enteroviruses in stools was associated with the appearance of islet autoimmunity in the Type 1 Diabetes Prediction and Prevention study in Finland.MethodsAltogether, 1673 longitudinal stool samples from 129 case children who turned positive for multiple islet autoantibodies and 3108 stool samples from 282 matched control children were screened for the presence of enterovirus RNA using RT-PCR. Viral genotype was detected by sequencing.ResultsCase children had more enterovirus infections than control children (0.8 vs 0.6 infections per child). Time-dependent analysis indicated that this excess of infections occurred more than 1xa0year before the first detection of islet autoantibodies (6.3 vs 2.1 infections per 10 follow-up years). No such difference was seen in infections occurring less than 1xa0year before islet autoantibody seroconversion or after seroconversion. The most frequent enterovirus types included coxsackievirus A4 (28% of genotyped viruses), coxsackievirus A2 (14%) and coxsackievirus A16 (11%).Conclusions/interpretationThe results suggest that enterovirus infections diagnosed by detecting viral RNA in stools are associated with the development of islet autoimmunity with a time lag of several months.

Circulating CXCR5+PD-1+ICOS+ Follicular T Helper Cells Are Increased Close to the Diagnosis of Type 1 Diabetes in Children With Multiple Autoantibodies

Although type 1 diabetes (T1D) is primarily perceived as a T cell–driven autoimmune disease, islet autoantibodies are the best currently available biomarker for autoimmunity and disease risk. These antibodies are produced by autoreactive B cells, the activation of which is largely dependent on the function of CD4+CXCR5+ follicular T helper cells (Tfh). In this study, we have comprehensively characterized the Tfh- as well as B-cell compartments in a large cohort of children with newly diagnosed T1D or at different stages of preclinical T1D. We demonstrate that the frequency of CXCR5+PD-1+ICOS+–activated circulating Tfh cells is increased both in children with newly diagnosed T1D and in autoantibody-positive at-risk children with impaired glucose tolerance. Interestingly, this increase was only evident in children positive for two or more biochemical autoantibodies. No alterations in the circulating B-cell compartment were observed in children with either prediabetes or diabetes. Our results demonstrate that Tfh activation is detectable in the peripheral blood close to the presentation of clinical T1D but only in a subgroup of children identifiable by positivity for multiple autoantibodies. These findings suggest a role for Tfh cells in the pathogenesis of human T1D and carry important implications for targeting Tfh cells and/or B cells therapeutically.

Serum 25-Hydroxyvitamin D Concentrations in Children Progressing to Autoimmunity and Clinical Type 1 Diabetes

CONTEXTnThe role of vitamin D in the development of type 1 diabetes (T1D) remains controversial.nnnOBJECTIVEnThe objective of the investigation was to study whether there are detectable differences in serum 25-hydroxyvitamin D (25[OH]D) concentrations between children who later progressed to T1D (cases) and matched children who remained nondiabetic and negative for islet autoantibodies (controls) when followed up from birth until disease onset.nnnDESIGNnA total of 3702 prospective serum samples from 252 children were measured for 25(OH)D from the age of 3 months onward using an enzyme immunoassay. Differences between the groups were compared by the mixed-model analysis of variance.nnnSETTINGnT1D prediction and prevention study clinics in Turku, Oulu, and Tampere University Hospitals, Finland, participated in the study.nnnPARTICIPANTSnBy the end of 2012, all 126 case children were diagnosed with T1D. The control children (n = 126) were matched for age, sex, study site, and human leukocyte antigen-HLA-DQ-conferred risk for T1D.nnnMAIN OUTCOME MEASUREnMedian circulating 25(OH)D concentration (nanomoles per liter) was measured.nnnRESULTSnThe patterns of variation in circulating 25(OH)D concentrations were similar between cases and controls and did not correlate with the age at seroconversion to autoantibody positivity (P = .79) or disease onset (P = .13). The median concentration of all collected samples did not differ between case and control children (66.6 nmol/L [range 14.0-262.8] vs 67.4 nmol/L [range 19.9-213.0]) P = .56).nnnCONCLUSIONSnThis study shows that serum 25(OH)D concentrations are not associated with the development of T1D in Finland.

Early childhood infections precede development of beta‐cell autoimmunity and type 1 diabetes in children with HLA‐conferred disease risk

The etiology of type 1 diabetes (T1D) is largely unknown. Infections and microbial exposures are believed to play a role in the pathogenesis and in the development of islet autoimmunity in genetically susceptible individuals.

Primary islet autoantibody at initial seroconversion and autoantibodies at diagnosis of type 1 diabetes as markers of disease heterogeneity

The relationship between patterns of islet autoantibodies at diagnosis and specificity of the first islet autoantibody at the initiation of autoimmunity was analyzed with the aim of identifying patterns informative of the primary autoantibodies.

Role of humoral beta-cell autoimmunity in type 1 diabetes.

Islet cell antibodies (ICA) were found for the first time more than 40u2009yr ago in patients with autoimmune endocrine deficiencies, including type 1 diabetes (T1D). ICA detected by indirect immunofluorescence represent a heterogeneous group of autoantibodies targeting a series of biochemical autoantigens, such as the protein tyrosine phosphatase related islet antigen 2 (IA‐2), the 65 kD isoform of glutamic acid decarboxylase (GA65), and zinc transporter 8 (ZnT8) as well as currently unidentified autoantigens. The general view is that the diabetes‐associated autoantibodies are not directly involved in beta‐cell destruction but function as biomarkers of an ongoing destructive process. The diabetes‐associated autoantibodies remain the strongest predictive marker for future development of T1D. Positivity for multiple (≥2) autoantibodies is highly predictive of clinical disease both among first‐degree relatives and in the general population. Autoantibody titers are highly variable during the preclinical phase, but in many cases the titers tend to decrease before diagnosis. The first signs of beta‐cell autoimmunity may appear early during the first months of life. The majority of those individuals diagnosed with T1D before puberty seroconvert to autoantibody positivity before the age of 3 yr. The natural course and duration of preclinical diabetes vary substantially from one individual to another. The characteristics of the isotype‐specific response during preclinical diabetes appear to be antigen‐specific. Diabetes‐associated autoantibodies may be useful surrogate markers of the subsequent development of T1D in primary prevention trials. T1D may occur, albeit rarely, in the absence of any signs of humoral autoimmunity at diagnosis.

Ketoacidosis at diagnosis of type 1 diabetes: Effect of prospective studies with newborn genetic screening and follow up of risk children

We studied the frequency of diabetic ketoacidosis (DKA) in children at diagnosis of type 1 diabetes (T1D) in a region where newborn infants have since 1995 been recruited for genetic screening for human leukocyte antigen (HLA)‐conferred disease susceptibility and prospective follow up. The aim was to study whether participation in newborn screening and follow up affected the frequency of DKA, and to follow the time trends in DKA frequency. We first included children born in Oulu University Hospital since 1995 when the prospective studies have been ongoing and diagnosed with T1D <15 years by 2015 (study cohort 1, n = 517). Secondly, we included all children diagnosed with T1D <15 years in this center during 2002‐2014 (study cohort 2, n = 579). Children who had an increased genetic risk for T1D and participated in prospective follow up had low frequency of DKA at diagnosis (5.0%). DKA was present in 22.7% of patients not screened for genetic risk, 26.7% of those who were screened but had not an increased risk and 23.4% of children with increased genetic risk but who were not followed up. In study cohort 2 the overall frequency of DKA was 18.5% (13.0% in children <5 years, 14.0% in children 5‐10 years and 28.6% in children ≥10 years at diagnosis; P<.001). In children <2 years the frequency of DKA was 17.1%. Participation in prospective follow‐up studies reduces the frequency of DKA in children at diagnosis of T1D, but genetic screening alone does not decrease DKA risk.

Effect of Hydrolyzed Infant Formula vs Conventional Formula on Risk of Type 1 Diabetes: The TRIGR Randomized Clinical Trial

Importance Early exposure to complex dietary proteins may increase the risk of type 1 diabetes in children with genetic disease susceptibility. There are no intact proteins in extensively hydrolyzed formulas. Objective To test the hypothesis that weaning to an extensively hydrolyzed formula decreases the cumulative incidence of type 1 diabetes in young children. Design, Setting, and Participants An international double-blind randomized clinical trial of 2159 infants with human leukocyte antigen–conferred disease susceptibility and a first-degree relative with type 1 diabetes recruited from May 2002 to January 2007 in 78 study centers in 15 countries; 1081 were randomized to be weaned to the extensively hydrolyzed casein formula and 1078 to a conventional formula. The follow-up of the participants ended on February 28, 2017. Interventions The participants received either a casein hydrolysate or a conventional adapted cow’s milk formula supplemented with 20% of the casein hydrolysate. The minimum duration of study formula exposure was 60 days by 6 to 8 months of age. Main Outcomes and Measures Primary outcome was type 1 diabetes diagnosed according to World Health Organization criteria. Secondary outcomes included age at diabetes diagnosis and safety (adverse events). Results Among 2159 newborn infants (1021 female [47.3%]) who were randomized, 1744 (80.8%) completed the trial. The participants were observed for a median of 11.5 years (quartile [Q] 1-Q3, 10.2-12.8). The absolute risk of type 1 diabetes was 8.4% among those randomized to the casein hydrolysate (nu2009=u200991) vs 7.6% among those randomized to the conventional formula (nu2009=u200982) (difference, 0.8% [95% CI, −1.6% to 3.2%]). The hazard ratio for type 1 diabetes adjusted for human leukocyte antigen risk group, duration of breastfeeding, duration of study formula consumption, sex, and region while treating study center as a random effect was 1.1 (95% CI, 0.8 to 1.5; Pu2009=u2009.46). The median age at diagnosis of type 1 diabetes was similar in the 2 groups (6.0 years [Q1-Q3, 3.1-8.9] vs 5.8 years [Q1-Q3, 2.6-9.1]; difference, 0.2 years [95% CI, −0.9 to 1.2]). Upper respiratory infections were the most common adverse event reported (frequency, 0.48 events/year in the hydrolysate group and 0.50 events/year in the control group). Conclusions and Relevance Among infants at risk for type 1 diabetes, weaning to a hydrolyzed formula compared with a conventional formula did not reduce the cumulative incidence of type 1 diabetes after median follow-up for 11.5 years. These findings do not support a need to revise the dietary recommendations for infants at risk for type 1 diabetes. Trial Registration clinicaltrials.gov Identifier: NCT00179777

Imbalance of bacteriome profiles within the Finnish Diabetes Prediction and Prevention study: Parallel use of 16S profiling and virome sequencing in stool samples from children with islet autoimmunity and matched controls

We set out to explore associations between the stool bacteriome profiles and early‐onset islet autoimmunity, taking into account the interactions with the virus component of the microbiome.